U.S. patent number 5,622,552 [Application Number 08/641,625] was granted by the patent office on 1997-04-22 for glass ionomer cement compositions and restorative methods.
This patent grant is currently assigned to Mion International Corp.. Invention is credited to Thomas J. Arnold.
United States Patent |
5,622,552 |
Arnold |
April 22, 1997 |
Glass ionomer cement compositions and restorative methods
Abstract
A restoration for restoring a lesion in a tooth and method for
making the same. The restoration comprises a layer of glass ionomer
cement bonded to the lesion and a layer of amalgam disposed on the
layer of glass ionomer cement. The restoration is formed by the
process of applying a layer of wet glass ionomer cement on the
lesion, placing a wet dental amalgam directly on the wet glass
ionomer cement, and allowing the wet glass ionomer cement and the
wet amalgam to harden to bond the amalgam to the tooth. Various
modifications to the glass ionomer cement are disclosed to either
improve the bond of the restoration's amalgam to the tooth or to
enhance the cement's use in various dental procedures. Also
disclosed are various dental procedures using the restoration and
method of making the restoration which results in the resolution of
certain shortcomings of current like procedures.
Inventors: |
Arnold; Thomas J. (Winslow,
IN) |
Assignee: |
Mion International Corp.
(Winslow, IN)
|
Family
ID: |
27568382 |
Appl.
No.: |
08/641,625 |
Filed: |
May 2, 1996 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
492273 |
Jun 19, 1995 |
|
|
|
|
313885 |
Sep 28, 1994 |
5427613 |
Jun 27, 1995 |
|
|
79332 |
Jun 18, 1993 |
5382284 |
Jan 17, 1994 |
|
|
942375 |
Sep 9, 1992 |
5252122 |
|
|
|
872501 |
Apr 23, 1992 |
5252121 |
|
|
|
991112 |
Dec 16, 1992 |
5273574 |
|
|
|
942375 |
|
|
|
|
|
748679 |
Aug 22, 1991 |
|
|
|
|
872501 |
|
|
|
|
|
748679 |
|
|
|
|
|
Current U.S.
Class: |
106/35;
433/228.1 |
Current CPC
Class: |
A61C
5/30 (20170201); A61K 6/887 (20200101); A61K
6/30 (20200101); A61K 6/20 (20200101); A61K
6/77 (20200101) |
Current International
Class: |
A61K
6/02 (20060101); A61K 6/05 (20060101); A61K
6/083 (20060101); A61C 005/00 () |
Field of
Search: |
;106/35 ;344/228.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
56-03637 |
|
Jan 1981 |
|
JP |
|
62-231668 |
|
Oct 1987 |
|
JP |
|
2275731 |
|
Nov 1990 |
|
JP |
|
Other References
Ketac-Cem Radiopaque Product Bulletin --no date available. .
Johnson et al, "Dentin Bonding Systems: A Review of Current
Products and Techniques" JADA, vol. 122, Jul. 1991. .
Elliott et al., Physical & Mechanical Properties of
Glass-Ionomer Cements, British Polymer Journal, no month available
1975, 7:297-306. .
Mitra, Adhesion to Dentin & Physical Properties of a
Light-cured Glass ionomer Liner/Base, Journal of Dental Research
70(1):72-74, Jan. 1991. .
Nathanson et al., The Significance of Retention in Post and Core
Restorations, PP&A, The AACD Symposium Edition, vol. 5, No. 3,
82-89, Apr. 1993. .
Browne et al., Soluble Aluminum Silicates: Stoichiometry, Stability
and Implications of Environmental Geochemistry, Science, vol.
256:1667-1670, 19 Jun. 1992. .
Wasson et al., New Aspects of the Setting of Glass-Ionomer Cements,
Journal of Dental Research 72(2):481-483, Feb. 1993. .
Swift, Jr., A review of dentin bonding, General Dentistry,
Sep.-Oct. 1988:396-399. .
International Publ. No. WO92/11837, Adhesive Amalgam System,
Published 23 Jul. 1992. .
Covey, David A. and Moon, P.C., "Shear bond strength of amalgam
bonded to dentin", American Journal of Dentistry, Feb., 1991. .
Hotz, The Bonding of Glass Ionomer Cements to Metal and Tooth
Substrates, British Dental Journal, no month available 1978 142;
41-47. .
Johnson, Denting Bonding Systems: A Review of Current Products and
Techniques, the Journal of the ADA no month available 1991;
122:34-41. .
Matis, et al., How Finishing Affects Glass Ionomers, Journal of the
American Dental Assoc., no month available 1991; 122:43-46. .
New Era of Composite Bonding, Dentistry Today, Jun./Jul. 1991, pp.
32, 34. .
New Product--Adhesive System, Dental Products Report, Sep., 1991.
.
SHOFU Advertisement, Dental Products Report, Sep. 1991, p. 65.
.
Dentistry Techniques, Dental Products Report, Sep. 1991, pp. 74-75.
.
Retentive Pins . . . Are they everything they're cracked up to be?,
Advertisement, American Dental Association News, no month available
1991; 22, 14: p. 15. .
Amalgambond--The first bonding agent for amalgam, Advertisement,
American Dental Association News, no month available 1991; 22.13;
p. 28. .
Starting today, you may never have to re-cement again . . . ever.
Advertisement, Dentistry today, no month available 1991; 10,6: p.
17. .
Mojan et al., Maximum Bond Strength of Dental Luting Cement to
amalgam Alloy, Journal of Dental Research, Nov. 1989;
68(11):1545-1549. .
Aboush et al., An evaluation of the bonding of glass-ionomer
restorations to dentine and amalgam, British dental Journal, no
month available 1986; 16, 179-184. .
Gilmore et al., Operative Dentistry, C.V. Mosby Company, no month
available 1983; pp. 196-200, 279-281. .
Staninec et al., Bonding of Amalgram to tooth structure: Tensile
adhesion and microleakage tests; Journal of Prosthetic Dentistry;
59:4; Apr. 1988; pp. 397-402. .
Torii et al., Inhibition in Vitro of Caries around amalgam.
Restorations by Bonding Amalgam to Tooth Structure; Operative
Dentistry; 14; no month available 1989; pp. 142-148. .
Shimizu et al., Bond Strength between Amalgam and Tooth Hard
Tissues with Application of Flouride, Glass Ionomer Cement and . .
. , Dental Materials Journal; 52; no month available 1986; pp.
225-232. .
Varga et al., Bonding of Amalgam Filling to Tooth Cavity with
Adhesive Resin; Dental Materials Journal; 5:2; no month available
1986; pp. 158-164. .
Lacy et al., The bonded amalgam restoration; Quintessence
International; 20:7; no month available 1989, pp. 521-524. .
Cooley et al., Bond strength of resin to amalgam as affected by
surface finish; Quintessence International; 20:4; pp. 237-239, no
month available 1989. .
Hibler et al.; Bond Strength Comparisons of Repaired dental
Amalgams; Quintessence International; 19:6; no month available
1989; pp. 411-415. .
Yu et al., Experimental use of a bonding agent to reduce marginal
microleakage in amalgam restorations; Quintessence International;
18:11; no month available 1987; pp. 783, 787. .
Colon et al., Les amalgames colles: technique diretc et indirecte;
Revue D'Odonto Stomatologie; 16:1; no month available 1987; pp.
9-18. .
Warren et al., Bonding amalgam to glass ionomer with PAA; Dental
Materials; 4; no month available 1988; pp. 191-196. .
Stevenson, Modified Bonded Amalgam Technique (letter to the
editor); British Dental Journal; Dec. 24, 1983; p. 401. .
The Government Chemist Plays Host; British Dental Journal; Apr. 23,
1983; p. 268. .
Braden, The Effect of Technology on Clinical Practice, Jul. 1 to 3,
1983. .
Pearson, Finishing of Glass-Ionomer Cements; British Dental
Journal; 155; no month available 1983; pp. 226-228. .
Prodger et al., ASPA Adhesion Study; British Dental Journal; 143,
no month available 1977; pp. 266-274. .
Dentist's Desk Reference: Materials, Instruments and Equipment;
American Dental Association; no month available 1981, pp. Preface
& 84-54. .
*Expansion of the Acceptance Program for dental materials and
devices; glass Ionomer cements; JADA; 99; Aug. 1979; pp. 227-228.
.
Reported Sensitivity to glass ionomer luting cements; JADA; 109;
Sep. 1984; p. 476. .
Status report on the glass ionomer cements; JADA; 99; Aug. 1979;
pp. 221-224. .
Dentist's Desk Reference; Materials, Instruments and equipment;
American Dental association; no month available 1983; pp. Preface
& 118-119. .
Gilmore et al., Operative Dentistry; no month available 1973; pp.
64-95. .
Cardosa et al., Low-Silver amalgam restoration; A two-year clinical
evaluation, Dental Materials, Jul. 1989; 5:277-80. .
Osborn, Clinical Assessment of 14 amalgam alloys, General
Dentistry, May-Jun. 1990:206-208. .
Powell et al., Effect of Admixed Indium on Mercury Vapor Release
from Dental Amalgam, Journal of Dental Research, Aug. 1989;
68(8):123;123. .
Aboush et al., The bonding of glass ionomer cements to dental
amalgam British Dental Journal, no month available 1989;
166:255-257. .
Mercurial Debata, Science; d55(13):1356-1357, Mar. 13, 1992. .
Fasbinder et al., Tensile Bond Strength of Dental Adhesives to
Dentin and Enamel, Dental Materials, Jul. 1989; 5:272-276. .
Curtis, The Use of Dental Amalgam--An Art or a Science?, 1992
Jul./Aug. Dental Update pp. 239-245. .
Watson, The interfacial region of the tooth/glass ionomer
restoration: A confocal optical microscope study, Am J Dent no
month available 1991; 4: 303-310. .
Stookey et al., Studies Concerning the Polishing Properties of
Ziconium Silicate on Enamel Journal of Peridontal, no month
available 1966; 37(3):200-207. .
Anderson et al., Effects of Zirconium Silicate Chewing Gum on
Plaque and Gingivitis, Quintessence International, no month
available 1990:21(6):479-489. .
Stookey et al, Studies Concerning the Biological Properties of
Zirconium Silicate, Journal of Peridontal, no month available 1967;
38(1):53-63. .
Swift et al., Use of Glass Ionomer Cements by Iowa Dentist, General
Dentistry, Nov./Dec. 1990; 450-453. .
Shannon, A Punice-Zirconium Silicate Prophylaxis Past Containing 2%
Stannous Fluoride in Water-Free Solution, Pharmocology and
Therapeutics in Dentistry, no month available 1970; 1:24-30. .
Fleming et al., Effects of Caries of Self-Application of a
Zirconium Past Containing 9% Stannous Fluoride, Community Dent.
Oral Epidemiol., no month available 1976; 4:142-148. .
Elliott et al., Physical and Mechanical Properties of Glass Ionomer
Cements, British Polymer Journal, no month available 1975, 9,
297-306..
|
Primary Examiner: Einsmann; Margaret
Attorney, Agent or Firm: Ice Miller Donadio & Ryan
Gridley; Doreen J. Overhauser; Paul B.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This is a continuation of application Ser. No. 08/492,273, filed
Jun. 19, 1995, which is a divisional application of application
Ser. No. 08/313,885, filed Sep. 28, 1994, now U.S. Pat. No.
5,427,613, issued Jun. 27, 1995, which was a divisional of
application Ser. No. 08/079,332, filed Jun. 18, 1993, now U.S. Pat.
No. 5,382,284, issued Jan. 17, 1994, which is a
continuation-in-part of application Ser. No. 07/942,375, filed Sep.
9, 1992, now U.S. Pat. No. 5,252,122, which is a continuation of
application Ser. No. 07/748,679, filed Aug. 22, 1991, abandoned;
Ser. No. 07/872,501, filed Apr. 23, 1992, now U.S. Pat. No.
5,252,121, which is a continuation-in-part of application Ser. No.
07/748,679, filed Aug. 22, 1991, abandoned; and Ser. No.
07/991,112, filed Dec. 16, 1992, now U.S. Pat. No. 5,273,574, which
is a continuation-in-part of application Ser. No. 07/942,375, filed
Sep. 9, 1992, now U.S. Pat. No. 5,252,122, which is a continuation
of application Ser. No. 07/748,679, filed Aug. 22, 1991, abandoned.
Claims
What is claimed is:
1. A method of restoring a tooth, comprising the steps of:
applying an etchant or primer to a tooth and subsequently applying
a wet glass ionomer cement to said tooth;
placing a wet dental amalgam directly on the wet glass ionomer
cement; and
allowing the wet glass ionomer cement and the wet dental amalgam to
harden, thereby bonding the amalgam to the tooth.
2. The method of claim 1 further comprising, prior to the
application of the wet glass ionomer cement, the steps of:
providing an etchant; and
etching the tooth.
3. The method of claim 1 further comprising, prior to the
application of the wet glass ionomer cement, the steps of:
providing a dental primer; and
applying the primer to the tooth.
4. A method of restoring a tooth, comprising the steps of:
applying a wet carboxylate-containing adhesive directly to the
tooth;
placing a wet amalgam directly on the wet-carboxylate containing
adhesive; and
allowing the wet carboxylate-containing adhesive and the wet
amalgam to harden, thereby ionically bonding the amalgam to the
tooth.
5. The method of claim 4 wherein the adhesive comprises a glass
ionomer cement.
6. The method of claim 4 wherein the adhesive includes an acrylic
cement.
7. A method of sealing a surface of a tooth, comprising the steps
of:
applying a layer of wet glass ionomer cement on the surface of the
tooth to be sealed;
placing a layer of wet amalgam directly on the wet glass ionomer
cement enabling the glass ionomer cement to bond the amalgam to the
tooth; and
allowing the wet glass ionomer cement and the wet amalgam to harden
to thereby bond the amalgam to the tooth to form a seal.
Description
FIELD OF THE INVENTION
This invention relates to dental restorations, and, in particular,
to dental restorations using glass ionomer cement and amalgam.
BACKGROUND OF THE INVENTION
Since its introduction to the United States in the late 1970's,
glass ionomer cements have gained a great deal of popularity for
use in various dental procedures. The interest in using glass
ionomer cements for a myriad of purposes stems from the cement's
ability to bond to both dentin and enamel, the fact that the cement
is tooth-colored when hardened, and because glass ionomer cements
generally contain fluorides which are thought to minimize the
occurrence of decay to the tooth surface to which the glass ionomer
cement is applied. Initially, glass ionomer cements were generally
used for restorations. These glass ionomer cements, known as Type
II glass ionomer cements, are of a larger particulate matter than
are the Type I glass ionomer cements used for other purposes. When
these Type II glass ionomer cements are used as a restoration
material, the lesion in a tooth is prepared by standard techniques
as may be performed for cavity preparation for the placement of an
amalgam restoration thereon; however, it may not be necessary to
create an undercut for a glass ionomer restoration. Care must be
taken to make certain that the preparation is free of moisture as
glass ionomer cement in such an application is extremely
susceptible to water contamination and dehydration during the
initial setting stage.
Type I glass ionomer cements are typically used as a base, liner,
or luting agent. When used for these purposes, the surface of the
tooth again must be substantially free from moisture during
application as well as throughout the hardening process of the
glass ionomer cement. In addition to its use as restorations, base,
liner or luting agent, glass ionomer cements are also used for
affixing restorations to a tooth. For composite restorations, such
as ceramic or porcelain prostheses, the glass ionomer cement is
allowed to harden and then is etched before placement of the
composite restoration thereon. For those restorations containing
metal, the glass ionomer cement need not be hardened first as wet
glass ionomer cement is known to adhere to cast metals.
Glass ionomer cements are generally comprised of a powder component
containing aluminosilicate and a liquid portion. Often the liquid
portion is expressed as containing polyacrylic acid, polymaleic
acid, polyitaconic acid, or a copolymer of at least two of the
acids. The liquid portion may also comprise carboxylate polymers or
carboxylic acid polymeric structures, such as those including
acrylic acid, maleic acid, crotonic acid, isocrotonic acid,
methacrylic acid, sorbic acid, cinnamic acid, fumaric acids and the
like. "New Aspects of the Setting of Glass-ionomer Cements," Wasson
et al., Journal of Dental Research; Vol. 72, No. 2, February, 1993;
pages 481-483. In all glass ionomer cements, the primary reactions
which cause the glass ionomer cement to harden is cross-linking,
i.e., the cross-linking of polycarboxylate chains by metal ions
from the glass. Also, during setting, the acids of the glass
ionomer cement dissolve the glass structure to release metal
constituents of the glass. Metal carboxylates are formed during the
setting process. This may be distinguished from the primary setting
reactions of acrylic cements which are other forms of
polymerization reactions. Though other forms of polymerization
reactions may occur in glass ionomer cements, these reactions are
secondary to the cross-linking reactions of the glass ionomer
cement.
Recently, it was discovered that wet glass ionomer cement bonds
well with wet amalgam. As disclosed in U.S. patent application Ser.
No. 07/942,375, filed Sep. 9, 1992, now U.S. Pat. No. 5,252,122 a
dental restoration is formed by applying a layer of wet glass
ionomer cement to a lesion in a tooth, placing a layer of wet
amalgam directly on the layer of wet glass ionomer cement, and
allowing the cement and the amalgam to harden to thereby bond the
amalgam to the tooth. Such a restoration is beneficial in that the
cavity preparation need not be undercut for the placement of an
amalgam restoration. Further, the glass ionomer cement does not
appear to be as moisture sensitive in such a procedure. Finally,
the creation of the restoration is less time consuming than is a
restoration in which the glass ionomer cement is hardened and then
etched before the lesion is filled with amalgam.
Because glass ionomer cements have so many appealing qualities to
the dental profession, numerous variations of glass ionomer cements
have been developed to enhance particular properties of the glass
ionomer cements for specific applications. For example, U.S. Pat.
No. 4,738,722, discloses a glass ionomer cement containing
additives such as zinc oxide and titanium oxide. These additives
improve the glass ionomer cement by eliminating pulpal sensitivity
and also affect the setting time of the cement. Specifically,
reducing the setting time of the cement with the introduction of
these additives is beneficial when the glass ionomer cement is used
as a base, liner, or luting agent wherein it is desirable to have a
quick setting cement for the completion of further procedures
thereafter.
In U.S. Pat. No. 4,064,629, large metal particles are added to a
glass ionomer cement. In this manner when the cement is used as a
base or liner for an amalgam restoration, application of a wet
amalgam to a hardened glass ionomer cement essentially results in
the cross-amalgamation of the mercury in the amalgam with the large
metal particles in the cement. This additive assists in
strengthening the bond between the hardened glass ionomer cement
base and the amalgam restoration.
Another approach to strengthening the glass ionomer cement without
effecting its adhesive properties is disclosed in U.S. Pat. No.
4,738,722. Specifically, manufacturers have been known to add the
powder component of an amalgam to the glass ionomer cement. Such an
additive may be particularly helpful when using a glass ionomer
cement as a restoration. Yet another additive is disclosed in
Japanese Patent No. 2,275,731. In this patent, zinc oxide and
zirconium oxide are added to the glass ionomer cement to improve
its resistance to disintegration and crushing and to improve its
hardening time.
Another problem associated with glass ionomer cement is its
tendency to shrink as it dries in relation to a reduction in the
environmental humidity. In resnonse to this problem, an additive
mixture to glass ionomer cement comprising quartz sand,
cristobalite flour and zirconium silicate was added in a study
discussed in the article "Physical and Mechanical Properties of
Glass-Ionomer Cements", Elliott, et al., British Polymer Journal,
1975, 9, 297-306. Though the additive mixture assists in reducing
shrinkage in a less humid environment, it was also found to reduce
the compressive strength of the cement.
Disclosed in U.S. patent application Ser. No. 07/991,112, filed
Dec. 16, 1992, now U.S. Pat. No. 5,273,574 is an additive
comprising zircon for use with the wet glass ionomer cement to wet
amalgam restorative method of U.S. patent application Ser. No.
07/942,375, now U.S. Pat. No. 5,252,122. The zircon additive, in
this application of glass ionomer cement, is thought not to
interfere with any of the normal chemical reactions of the glass
ionomer cement while allowing the practitioner to adjust the color,
handling characteristics, and the setting time of the cement.
In addition to modifying the glass ionomer cement, improvements
have been made with regard to the wet glass ionomer cement to wet
amalgam bond by mixing an additive to the amalgam. Specifically, in
U.S. patent application Ser. No. 07/872,501, filed Apr. 23, 1992,
now U.S. Pat. No. 5,252,121, additives from the group of metal
salts, metal bases and metal oxides are added to the amalgam to
improve such a bond. Such an additive may comprise, for example,
the powder component of a polycarboxylate cement.
With each of the various dental procedures for which glass ionomer
cements are known to be used, it is desired to improve upon certain
characteristics of this cement depending on the particular use of
the cement. As previously noted, a relatively quick setting time is
desired when the glass ionomer cement is being used as a base,
liner or luting agent or when used to affix a composite restoration
to a tooth. This desire is based on the requirement for the glass
ionomer cement to first harden prior to the completion of
subsequent dental procedures. Further, any improvements which can
be made for any use of a glass ionomer cement which inhibits
secondary caries or which strengthens the glass ionomer cement are
generally desirable.
In addition to serving as a restoration, amalgam has been used for
a variety of dental procedures. For example, there are instances in
which it is desirable to build an amalgam post or an amalgam core
for attachment of a prosthesis to the tooth. A post is defined as a
solid structure which extends into a hole in the tooth, generally a
hole formed in the root canal of the tooth. A core extends above
the root tooth surface and is generally of larger mass than is a
post. Should amalgam be used to build a post or a core, generally,
the tooth surface must be undercut to mechanically retain the
amalgam within the undercut tooth structure after the amalgam has
hardened. Such undercutting is not feasible in all instances
depending on the tooth structure remaining and from which the post
or core is to extend. Thus, the use of amalgam posts and/or cores
may not always be feasible even though desirable for their known
strength and adaptability or formability within the tooth.
Therefore, it is desired to develop a method for building an
amalgam post and/or an amalgam core which does not require
undercutting of the remaining tooth structure.
When an amalgam core is used for the application of a prosthesis
thereon, difficulty for the dentist and the patient arises in the
amount of time usually required for the completion of such a
procedure. First, in many instances this involves a multi-step
process whereby the core is cemented to the tooth, or, alternately,
may involve the application of an amalgam core as previously
discussed. In either instance, the core or cement must be allowed
to harden. Then, before the prosthesis may be applied to the core
with a cement, the core must be properly shaped for the prosthesis
or the prosthesis must be made to fit the shape of the core. Again,
a period of time expires in treatment. Now, the cement can be used
to affix the prosthesis to the core to harden. It is therefore
desirable to develop a method for applying both a core and a
prosthesis thereon which consumes less time than is currently
required.
Another dental procedure to which improvements may be made is that
of post cementation. Generally, a hole is prepared in the canal of
the tooth for receipt of a post. The cement is spinned or applied
into the hole and the post is coated with a cement. The post is
then placed into the hole and the cement is allowed to harden such
that the cement holds the post's place within the hole. For
stainless steel and titanium posts, a variety of cements may be
used for this purpose; however, for these posts, cements are known
to be deficient to adequately provide the desired rigidity and
strength. Therefore, it is desired to provide a method of post
cementation that may be utilized with a post of any material to
increase the stability with which the post is retained within the
hole.
The application of sealants to teeth often poses problems desired
to be overcome. In many instances, sealants are applied to a
child's teeth with the intent of protecting the tooth. Regardless
of the age of the patient, the sealant, usually an acrylic, is
applied after etching, rinsing and drying the tooth. The sealant is
then allowed to harden. This procedure may take upwards of three
minutes to complete. During this period, it is very difficult to
isolate moisture from the area to be sealed. Such moisture may
reduce the bond between the sealant and the tooth. Therefore, it is
desired to develop a procedure for sealing teeth which is less time
consuming than the described procedure. In addition, it is desired
to provide a sealant which may be used without etching the tooth
surface to be sealed. Also, the life expectancy of acrylic sealants
is typically five years. There are instances when this period of
time is not sufficient and it is therefore desired to develop a
sealant having a longer life span. Finally, acrylic sealants do not
chemically inhibit the development of secondary caries. Therefore,
it is desired to inhibit such decay with the use of a sealant
containing fluorides or like decay-inhibiting materials.
There are some instances in which it is desired to splint two teeth
together. Such a procedure may be necessary, for example, should a
tooth be jarred loose as may be caused by an accident. Generally,
the procedure for splinting teeth together today involves cementing
the adjacent teeth together by applying crowns thereon. Such a
procedure is therefore costly. It is desired, then, to reduce the
cost of splinting teeth together as may be necessary to resolve a
temporary problem or when the patient is unable to afford a more
expensive procedure.
In summary, glass ionomer cements have been used for a variety of
purposes since their introduction. Variations on the chemical
composition of the glass ionomer cements have proved helpful in the
use of glass ionomer cements for particular dental procedures and
yet further improvements are desired. In addition, there are
numerous dental procedures for which cementing techniques may be
utilized and which as currently performed may exhibit difficulties,
inconveniences or problems which are desirable to be addressed in
the development of new or improved methods.
OBJECTS OF THE INVENTION
Accordingly, it is one object of the present invention to provide
an additive for glass ionomer cement which improves the strength of
the cement without altering its chemical reactions.
It is another object of the present invention to provide a method
for building an amalgam core or an amalgam post which does not
require that the remaining tooth structure be undercut.
It is still another object of the present invention to provide a
method for building a core and attaching a prosthesis thereto that
is less time consuming to perform than is required with current
procedures.
It is another object of the present invention to provide a post
cementation method that may be used to cement any post (including
those made of stainless steel or titanium) and which results in an
increase in the retentive forces.
It is still another object of the present invention to provide a
dental sealant which is less time consuming to apply than are
acrylic sealants, is capable of being used to seal adjoining
grooves in the tooth surface to be sealed without etching the
tooth, has an increased life expectancy over acrylic sealants and
inhibits the development of decay.
It is yet another object of the present invention to provide a
method for splinting adjacent teeth together which is less
expensive than the application of a crown over the teeth.
SUMMARY OF THE INVENTION
A restoration for restoring a lesion in a tooth comprises a layer
of glass ionomer cement bonded to the lesion and a layer of amalgam
disposed on the layer of glass ionomer cement. The restoration is
formed by the process of applying a layer of wet glass ionomer
cement on the lesion, placing a wet amalgam directly the layer of
wet glass ionomer cement, and allowing the cement and the amalgam
to harden to thereby bond the amalgam to the tooth. This process is
also referred to herein as the wet-to-wet process or method.
In one embodiment, the glass ionomer cement of the restoration
includes diamond microcrystals which increase the compressive
strength of the cement and which provides a mechanism whereby the
contraction of the cement during hardening can be controlled. By
controlling the contraction of the cement, the expansion of the
amalgam occurring during its hardening may be accommodated.
In another embodiment, the glass ionomer cement comprises an
antibiotic compound to assist in reducing the possibility of
secondary caries from the restoration. In yet another embodiment,
the glass ionomer cement contains at least one additive from the
group of metals, metal salts and metal oxides to improve the bond
strength of the restoration. Wet dental amalgam is mixed throughout
the cement in another embodiment of the glass ionomer cement to
further enhance the bond strength and to improve upon the cement's
compressive strength.
Various methods are presented herein in which the restoration
created by the wet-to-wet process is used to resolve shortcomings
of present dental procedures. An amalgam post or amalgam core is
formed by the wet-to-wet process, thereby eliminating the need to
undercut the tooth surface for retention of the amalgam. For
cementing posts within a canal hole in a tooth, the wet-to-wet
process is utilized to assist in retaining the post within the
canal hole. This post-cementation method may be used for posts made
of materials such as titanium which are presently difficult to
cement to a tooth. Also, the wet-to-wet method is used in affixing
a prosthesis to an amalgam core extending from the tooth which
reduces the amount of time necessary to complete such a procedure.
The wet-to-wet method is also used to quickly and easily seal a
tooth or teeth as well as adjoining grooves in the tooth with such
a sealant having an improved life expectancy and resistance to
decay when compared to acrylic sealants. In addition, the
wet-to-wet method is used to splint adjacent teeth together at a
cost that is significantly less than the application of a crown to
the adjacent teeth.
DETAILED DESCRIPTION
U.S. patent application Ser. No. 07/942,375, filed Sep. 9, 1992,
now U.S. Pat. No. 5,252,122, incorporated herein by reference,
discloses a method for restoring a lesion in a tooth as well as a
restoration formed by that method. Specifically, the method
involves the steps of applying wet glass ionomer cement to a
lesion, placing wet dental amalgam directly on the wet glass
ionomer cement, and allowing the wet glass ionomer cement and the
wet dental amalgam to harden. In this manner, the amalgam is bonded
to the tooth. The restoration formed by this method comprises a
layer of glass ionomer cement bonded to the tooth and a layer of
amalgam disposed on the layer of glass ionomer cement. The method
and restoration are advantageous in that no retentive pins or acid
etching is required for bonding an amalgam restoration to the
tooth. Also, a large lesion or cavity may be filled by such
restoration without requiring that the tooth be undercut for the
retention of such a restoration. Though disclosed as applicable to
a lesion, the method may utilized on any tooth surface. For
example, a portion of the tooth may be broken off and the method
used to restore the tooth to its desired form. The method may also
be used to form an amalgam veneer on any tooth surface and may even
be applied to a substantially vertical surface.
As previously mentioned herein, glass ionomer cements contain metal
carboxylates formed during the setting process of the cement. The
primary reaction causing the glass ionomer cement to harden is the
cross-linking of polycarboxylate chains by metal ions from the
glass. Thus, a glass ionomer cement when wet is a
carboxylate-containing cement. As used herein, and in the claims,
the term glass ionomer cement encompasses cements or adhesives
using this primary reaction of cross-linking. Further, because the
presence of metal carboxylates is critical to the formation of the
ionic bond of the amalgam to the tooth in the method of U.S. patent
application Ser. No. 07/942,375, now U.S. Pat. No. 5,252,122 (the
"wet-to-wet" method), the cement must necessarily be
carboxylate-containing. It is possible for a carboxylate-containing
cement or adhesive to be comprised of cements other than a pure
glass ionomer cement to achieve the desired bond. In addition to
cements comprising a glass ionomer cement and an additive or
additives thereto, the cement may comprise a mixture of different
types of cements and still be contemplated as within the scope of
the invention. For example, a mixture of glass ionomer cement and
an acrylic cement contains carboxylates and therefore may be
utilized in the wet-to-wet method.
It will be appreciated by those of skill in the art that the
wet-to-wet method does not require that the tooth to be restored
first be etched nor does a primer need to be applied. This results
in an expedient procedure for restoring a tooth. However, it is
possible that an etchant or primer is first applied to the tooth
prior to the application of the glass ionomer cement. Though the
application of an etchant and/or primer increases the time
necessary to create the restoration, it may be desirable should its
presence increase the bond of the amalgam to the tooth or should
the dentist's preferences dictate the use of an etchant or
primer.
Considering first the use of a primer, primers, sometimes referred
to as dentin pretreatment materials, are used with acrylic bonding
systems as well as in other dental restorative procedures. In
acrylic bonding systems, the tooth is first etched and then a
primer is applied to the tooth and allowed to harden. An acrylic
bonding agent is then disposed on the primer and then the amalgam
is applied to the bonding agent. Examples of primers used with
bonding agents include hydroxyethyl methacrylate (HEMA), HEMA and
glutaraldehyde, ferric acid, and phosphonated dimethacrylate
combined with ethanol, water and comphoroquinone. Though some
primers may reduce the bond strength of the ionic bond of the
amalgam to the tooth in the wet-to-wet method, other, such as
ferric chloride, may present ions which enhance the ionic bond of
the amalgam to the tooth.
Though glass ionomer cements bond well to dentin, a dentist may
desire to prepare the tooth surface with an etchant with the intent
of enhancing the bond of the restoration to the tooth. Examples of
etchants used today in dentin bonding systems as well as in other
restorative procedures include ether-acetone, hydrogen peroxide and
alcohol, citric acid, phosphoric acid and
ethylenediaminetetraacetic. Application of an etchant to the tooth
prior to the application of the glass ionomer cement is
contemplated to be within the scope of the invention as the glass
ionomer cement is still applied directly to the tooth and an ionic
bond between the amalgam and the tooth results from the application
of wet amalgam on the wet glass ionomer cement.
In terms of improvements to the glass ionomer cement as may be used
in the restoration and method (the "wet-to-wet" method) of U.S.
patent application Ser. No. 07/942,375, now U.S. Pat. No.
5,252,122, it is desirable for the glass ionomer cement to
accommodate the known expansion of amalgam during the amalgam's
hardening process. The expansion of amalgam is generally
advantageous in that it assists in sealing the amalgam restoration
to the tooth. It is therefore preferable that the glass ionomer
cement not hinder the early setting expansion of the amalgam for
this reason. By creating a glass ionomer cement which controls the
contraction while hardening at an amount substantially equivalent
to the dimensional changes of wet amalgam in early amalgamation,
the restorative bonding stress between the layer of hardened glass
ionomer cement and the layer of hardened amalgam are minimized. In
this manner, few gaps between the layers result to thereby improve
the bond of the glass ionomer cement to the amalgam as well as the
bond of the amalgam to the tooth.
Glass ionomer cements containing inert additives, i.e., those
additives which do not appear to interact with the chemical
reactions of the glass ionomer cement, have been found to assist in
minimizing the restorative bonding stress between the layer of
hardened glass ionomer cement and the layer of hardened amalgam.
Zircon (zirconia silicate) disclosed as an additive to glass
ionomer cement for the "wet-to-wet" method in U.S. patent
application Ser. No. 07/991,112, filed Dec. 16, 1992, now U.S. Pat.
No. 5,273,574, constitutes such an inert additive. Another inert
additive is diamond. According to the present invention, diamond
microcrystals are added to the glass ionomer cement for the purpose
of reducing the restorative bonding stress between the layer of
glass ionomer cement and the layer of amalgam, as well as for
improving the overall strength of the glass ionomer cement. This
"strength" refers to the cement's compressive strength and its
resistance to crushing and disintegration. A glass ionomer cement
comprising diamond microcrystals may be formed by adding diamond
microcrystals to either the powder component or the liquid
component of the glass ionomer cement prior to mixing the powder
and liquid together to form a wet cement. To result in a glass
ionomer cement having acceptable handling characteristics for a
variety of restorative purposes, diamond microcrystals comprise
from about 0.1% by weight to about 50% by weight of the total
weight of the cement. If, for example, the cement is to be utilized
as a restorative material for filling a cavity, a greater
percentage of diamond microcrystals is desirable. On the other
hand, for use as a base, liner, or luting agent, a lower percentage
of diamond microcrystals may be preferable. It is worthy to note
that the thickness of the resulting cement decreases with the
addition of diamond microcrystals. The additive's affect on
viscosity must also be taken into consideration when determining
the appropriate amount for use in a particular dental
procedure.
It will be appreciated by those of skill in the art that the
diamond microcrystals not only increase the strength of the glass
ionomer cement, but the diamond microcrystals do so without
interacting with the chemical reactions of the glass ionomer cement
during hardening. Thus, diamond microcrystals are desirable for a
variety of uses of glass ionomer cements including the "wet-to-wet"
method of restoring a lesion in a tooth disclosed in U.S. patent
application Ser. No. 07/942,375, now U.S. Pat. No. 5,252,122. Also,
the diamond microcrystals may be added to glass ionomer cements
used for other procedures well known in the art. For example, glass
ionomer cement containing diamond microcrystals may be used as a
base, as a liner, as a luting agent or as a restorative
material.
Because glass ionomer cements are carboxylate-containing
adhesives/cements, and because the primary reaction occurring
during the setting of the glass ionomer cement is the cross-linking
of polycarboxylate chains by metal ions from the glass,
improvements to the glass ionomer cement may also be made by adding
to the cement an additive or additives in the form of a metal base,
metal salt and/or metal oxide. The presence of these metal
additives further facilitate the cross-linking of polycarboxylates
with the metal ions of glass ionomer cement. Such an additive may
comprise from about 2% to about 50% by weight of the total weight
of the cement and may be added to either the liquid or powder
components of the glass ionomer cement. The metal, metal salt,
and/or metal oxide additive(s) may be a combination thereof and
assists in increasing the bond strength of wet glass ionomer cement
to wet amalgam.
One concern in creating an amalgam restoration is the potential for
the development of secondary caries. If decay develops between the
tooth and the amalgam restoration, replacement of the amalgam
restoration may eventually be required. When replacing an amalgam
restoration due to the presence of decay, the decay must
necessarily be removed, usually resulting in further loss of enamel
and/or dentin. In one embodiment of the present invention, an
antibiotic compound is added to the glass ionomer cement with the
intent of reducing the development of such secondary caries as well
as any residual primary caries. The antibiotic compound may be
added to either the powder or liquid components of the cement prior
to mixing or may be added to the mixed cement prior to the
application of the cement. Antibiotic compounds include
chlorhexidine, tetramycin, penicillin, keflex, ampicillin,
cephalosporin, and other antimicrobial or antibiotic agents. The
antibiotic additive may be added in an amount comprising from about
0.1% by weight to about 35% by weight of the total weight of the
glass ionomer cement. When used in conjunction with the
"wet-to-wet" restorative method of U.S. patent application Ser. No.
07/942,375, now U.S. Pat. No. 5,252,122, the glass ionomer cement
containing an antibiotic compound not only assists in bonding the
amalgam to the tooth, but provides an antimicrobial additive to
resist the development of secondary caries between the amalgam and
the tooth.
In another embodiment of the present invention, just triturated
dental amalgam is mixed throughout the glass ionomer cement. "Just
triturated" is intended to mean wet dental amalgam wherein the
amalgam powder and mercury components of the amalgam have been
mixed and the mixture has not yet amalgamated or hardened. By
adding wet amalgam to the glass ionomer cement in amounts from
about 20% by weight to about 70% by weight of the total weight of
the composition, a strong restorative material results.
Essentially, the wet-to-wet restorative method is utilized within
this restoration as the wet amalgam resides within the wet glass
ionomer cement. Such a composition has been found not to affect the
amalgamation process and the amalgam continues to amalgamate within
the glass ionomer cement, i.e. the amalgam within the glass ionomer
cement hardens in concert with the hardening of the glass ionomer
cement. For such a restorative material, the glass ionomer cement
may be of a composition which accommodates the expansion of the
amalgam within the glass ionomer cement such that a restoration
using this composition does not place undue stress on the lesion or
cavity in which the restoration is applied.
It will be appreciated by those of skill in the art that
restorative material comprising wet (just triturated) amalgam in
wet glass ionomer cement may be used for dental procedures
ordinarily requiring the use of glass ionomer cement alone. In
addition to using the restorative material as a restoration, it may
be used as a base, liner, core material, or luting agent. The
restorative material may also be used with the wet-to-wet
restorative method of the present invention.
As previously mentioned herein, there are numerous dental
procedures to which improvements may be made. As disclosed herein,
the wet-to-wet restorative method of the present invention may be
used to improve upon various dental procedures. In one embodiment
of the present invention, to create an amalgam post which is to
extend from a canal hole in a tooth, glass ionomer cement is used
to bond the amalgam post to the tooth according to the wet-to-wet
method. Specifically, by applying the wet glass ionomer cement to
the hole, packing the wet amalgam into the hole and allowing the
amalgam and cement to harden, an amalgam post is formed. The
resulting amalgam post may be used in concert with conventional
dental procedures requiring a post. It will be appreciated by those
of skill in the art that this amalgam post may extend directly
above the tooth surface without requiring the tooth surface be
undercut as is necessary when amalgam is applied without the use of
the wet-to-wet restorative method.
Similar to building an amalgam post, an amalgam core for a tooth
may be formed using the wet-to-wet method. By applying a layer of
wet glass ionomer cement to the tooth, and then applying a layer of
wet amalgam to the layer of wet glass ionomer cement such that the
wet amalgam extends above the root portion of the tooth, an amalgam
core is formed upon the hardening of the glass ionomer cement and
the amalgam. As with the building of amalgam posts, no undercutting
is required for building an amalgam core according to the present
invention. Of course, the amalgam core according to the present
invention may be used in conjunction with a support member, such as
a pin or post which extends above the tooth surface. By applying
the amalgam intended to form the core about a support member, the
support member is utilized to assist in holding the amalgam core in
place. It will be further appreciated that use of a support member
may be desired when restoring a large lesion or cavity using the
wet-to-wet method.
In another embodiment of the present invention, amalgam is used to
assist the cementation of a post into a tooth. Specifically, for a
tooth having a canal hole therein, a post having a length greater
than the depth of the hole is placed into the hole after wet cement
is applied to either the hole or the post or both. For example, the
cement may be spinned or applied into the hole and/or applied to
the portion of the post to be inserted into the canal hole. Use of
the cement holds the post in place in the hole. A portion of the
post extends above the tooth when placed in the hole. By placing
cement about the post at the point at which the post extends above
the hole and bonding a wet amalgam to the cement placed above the
hole, and allowing the amalgam to harden, the amalgam and cement
above the hole assist in retaining the post within the hole.
Various amalgam bonding agents may be employed as the cement above
the hole in this post cementation method, or tooth structure above
the hole may be undercut for retention of the amalgam about the
post and above the hole. The wet-to-wet method is also contemplated
for use in this post cementation method as well. Specifically, a
glass ionomer cement is used and the amalgam is applied to the
glass ionomer cement above the hole before the cement hardens. This
results in the bonding of the wet amalgam to the wet glass ionomer
cement. It will be appreciated by those of skill in the art that
cement may extrude from the hole after placing the post into the
canal hole. If such an extruded cement results, it is not necessary
to apply additional cement above the post as the extruded cement
may be used for the bonding purpose.
It will be appreciated that the amalgam applied above the canal
hole may also be bonded to the post itself. The post cementation
method may be particularly helpful when using an inert metal post
(e.g. titanium or gold) as cements generally do not adhere as well
to inert metal posts, even though amalgam bonds well with such
posts. Though the use of inert metal posts is desirable due to the
material's strength, it has been hindered due to the inability to
secure these posts within the hole. By using the post cementation
method described herein wherein the amalgam contacts the post above
the hole, the post is securely cemented within the hole by being
bonded to the amalgam which is in turn bonded to the tooth. It will
be appreciated by those of skill in the art that regardless of the
composition of the post, the placement of this amalgam cap at the
top of the hole about the post further assists in retaining the
post within the hole. This is true whether or not the amalgam
actually contacts and is bonded to the post itself.
The wet-to-wet restorative method of the present invention may also
be used to adhere an amalgam core to the tooth for the placement of
a prosthesis thereto. By placing wet glass ionomer cement on a
lesion in the tooth, packing the wet amalgam into the lesion such
that the wet amalgam contacts the wet glass ionomer cement, an
amalgam core is formed as previously described herein. A prosthesis
may be cemented to the amalgam core with wet glass ionomer cement
to form an amalgam core. Such a prosthesis may be, for example, a
crown or a bridge. It is also contemplated to be within the scope
of the invention to cement the prosthesis over an amalgam core
before the amalgam hardens. This significantly reduces the amount
of time required for the procedure of building a core and placing a
prosthesis thereon as is done in the prior art. Specifically, the
amalgam core may be applied directly over the glass ionomer cement
without waiting for the cement to harden. Also, the prosthesis may
be applied to the amalgam core before the amalgam hardens. It will
also be appreciated that a support member, such as a pin or a post,
may be used in conjunction with the method of affixing a prosthesis
to a core as discussed herein. Such a support member will further
assist in retaining the core and prosthesis in position.
To address problems associated with the use of acrylic sealants,
the wet-to-wet restorative method of the present invention may be
utilized. Specifically, by applying a layer of wet glass ionomer
cement on the surface of the tooth to be sealed, placing a layer of
wet amalgam directly on the wet glass ionomer cement thereby
enabling the glass ionomer cement to bond the amalgam to the tooth,
and allowing the glass ionomer cement and the wet amalgam to
harden, the amalgam is bonded to the tooth to form a seal. This
method results in several advantages over the application of
acrylic sealants. First, the sealing method of the present
invention is less time consuming than the method using acrylic
sealants. Also, the glass ionomer/amalgam sealant is capable of
sealing adjoining grooves in the tooth surface to be sealed without
etching the tooth. Because the sealing method of the present
invention may last a lifetime, it results in a seal having an
increased life expectancy over acrylic sealants which typically
only last for five (5) years. The glass ionomer/amalgam sealant
also inhibits the development of decay. This inhibition of decay
results from the fact that glass ionomer cements generally comprise
fluoride ions which resist the development of secondary caries.
In yet another embodiment of the present invention, the wet-to-wet
method may be used to splint two adjacent teeth together. The
splinting method utilizes the wet-to-wet restorative method. First,
wet glass ionomer cement is applied to adjacent surfaces of the
teeth. Then, a layer of wet amalgam is placed onto the wet glass
ionomer cement, and the cement and amalgam are allowed to harden.
In this manner, the adjacent teeth are bonded to each other upon
hardening of the cement and amalgam. A fastener, such as a
stainless steel wire, may be used with the splinting method of the
present invention to assist in splinting the adjacent teeth
together. By drilling a hole in each of the teeth and cementing the
ends of the fastener to the drilled holes prior to the application
of the wet glass ionomer cement, the glass ionomer cement and
amalgam is then applied about the fastener. This results in the
fastener joining the adjacent teeth together in addition to teeth
being bonded together by the application of the glass ionomer
cement and amalgam according to the wet-to-wet method of the
present invention.
It will be appreciated by those of skill in the art that the
splinting method of the present invention is less costly than is
the conventional solution of placing crowns over the adjacent
teeth. Further, the splinting procedure is easily performed in a
short amount of time and therefore offers a more viable solution
for a temporary problem to be resolved by splinting adjacent teeth
together.
* * * * *